1. Field of the Invention
The present invention relates to ion implantation, and more particularly, to an ion implantation method and an ion implantation apparatus (ion implanter).
2. Description of the Related Art
In semiconductor manufacturing processes, a process for implanting ions into a semiconductor wafer (hereinafter, referred to as an “ion implantation process”) is performed in a standard procedure for the purpose of changing conductivity, changing a crystalline structure of the semiconductor wafer, or the like. An apparatus used in the ion implantation process is generally called an ion implanter and has a function of generating an ion beam which is ionized by an ion source and then accelerated, and a function of transporting the ion beam to the semiconductor wafer and irradiating the above-described wafer with the ion beam.
The ion implanter is configured so that, for example, an ion source, an extraction electrode, a mass analysis magnet device, amass analysis slit, an acceleration/deceleration device, a wafer processing chamber, and the like are arranged along a beamline so as to implant ions into a wafer which is a semiconductor substrate.
In general, it is preferable that the state of an ion beam which is to be irradiated on a wafer be stable. However, in some cases, the state of the ion beam is changed due to various factors. Therefore, if components of the ion implanter are not controlled as needed after detecting the change of the ion beam by some means, it is difficult to securely manufacture a semiconductor having desired performance. Accordingly, an ion implanter having a Faraday cup for measuring a beam current of an ion beam at a desired timing is contrived.
Sometimes, in an ion implanter, a discharge event which can affect the ion beam may occur. The discharge event influences ion implantation by the ion beam and is one of factors causing a difference in performance of finally manufactured semiconductor products. Therefore, it is important to detect the discharge event in an ion implantation process. However, it is difficult to accurately detect the discharge event through the measurement of the beam current of the ion beam using only the above-described Faraday cup.